1. Field of the Invention
The present invention relates to measuring apparatuses and methods, processing apparatuses and methods, pattern forming apparatuses and methods, exposure apparatuses and methods, and device manufacturing methods, and more particularly to a measuring apparatus and a measuring method that measure position information of a movable body that moves within a plane, a processing apparatus and a processing method that perform a predetermined processing to an object mounted on a movable body that moves within a plane, a pattern forming apparatus that is equipped with the measuring apparatus or the processing apparatus and a pattern forming method that includes the measuring methods, an exposure apparatus and an exposure method that expose an object with an energy beam via an optical system, and a device manufacturing method in which either one of the measuring method, the processing method, the exposure apparatus or the exposure method is used.
2. Description of the Background Art
Conventionally, in a lithography process for manufacturing electron devices (microdevices) such as semiconductor devices (integrated circuits or the like) or liquid crystal display devices, exposure apparatuses such as a reduction projection exposure apparatus by a step-and-repeat method (a so-called stepper) and a projection exposure apparatus by a step-and-scan method (a so-called scanning stepper (which is also called a scanner)) are mainly used.
However, the surface of a wafer as a substrate to be exposed is not always flat due to, for example, undulation of the wafer or the like. Therefore, in the scanning exposure apparatus such as a scanner in particular, when transferring a reticle pattern to a certain shot area on the wafer by a scanning exposure method, a so-called focus-leveling control is performed, in which position information (focus information) of the wafer surface in an optical axis direction of a projection optical system at a plurality of detection points set in an exposure area is detected using, for example, a multipoint focal position detecting system (hereinafter, also referred to as a “multipoint AF system”) or the like, and based on the detection results, the position in the optical axis direction and the tilt of a table or a stage that holds the wafer is controlled so that the wafer surface constantly conforms to the image plane of the projection optical system within the exposure area (so that the wafer surface is within a range of depth of focus of the image plane) (e.g. refer to Kokai (Japanese Unexamined Patent Application Publication) No. 06-283403).
Meanwhile, in the stepper, the scanner or the like, the wavelength of used exposure light is getting shorter year by year due to finer integration circuit, and also the numerical aperture of a projection optical system is gradually getting larger (larger NA), which is intended to improve the resolution. On the other hand, there has been a possibility that the focus margin at the time of exposure operation becomes insufficient because a depth of focus becomes so narrow due to the shorter wavelength of exposure light and the larger NA of the projection optical system. Therefore, as a method of substantially shortening the exposure light wavelength and also increasing (widening) a depth of focus compared in the air, an exposure apparatus making use of a liquid immersion method has been gathering attention recently (refer to the pamphlet of International Publication No. 2004/053955).
However, in exposure apparatuses that makes use of the liquid immersion method, or other exposure apparatuses in which a distance (working distance) between the lower end surface of the projection optical system and the wafer is short, it is difficult to place the multipoint AF system described above in the vicinity of the projection optical system. Meanwhile, in the exposure apparatuses, it is required that highly accurate surface position control of the wafer is realized in order to achieve exposure with high precision, and besides, high throughput is also required.
Further, in the stepper, the scanner or the like, position measurement of a stage that holds a substrate to be exposed (e.g. a wafer) is generally performed using a laser interferometer with high resolution. However, an optical path of a beam of the laser interferometer that measures the position of the stage is as long as several hundred mm or more, and in addition, position control of the stage with higher accuracy has been required due to finer patterns to cope with semiconductor devices with higher integration, and therefore, short-term fluctuation of measurement values of the laser interferometer which is caused by temperature fluctuations (air fluctuations) of the atmosphere on the beam path of the laser interferometer is becoming unignorable now.